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Vol. IX, No. 1.] Sponges of the Lake of Tiberias. 77 
N.S.) 
differ considerably from those of European, tropical African or 
tropical Asiatic fresh waters. The one endemic genus (Corti- 
spongilla) appears to be related to Pachydictyum, which is en- 
demic in a lake inCelebes; but the relationship may not be very 
close. The genus Nudospongilla, if it is to be accepted as a 
natural group, is probably of wide distribution in the hotter 
parts of the Old World, but none of the species found in the 
ake of Tiberias exhibit a clear connection with any species 
from elsewhere. It is possible, moreover, that N. mappa has 
some actual affinity with Grimm’s genus Metschnikowia, which 
is only known from the Caspian Sea. The fact that the race of 
Ephydatia fluviatilis found in the lake is distinct from the 
typical European form of the species is in itself evidence of 
but has produced comparatively few local races. 
such relationship as exists is with Syria only, for the race is not 
known to occur any further afield. 
3. CLASSIFICATION OF THE POTAMOLEPIDINAE AND OF SOME 
OBSCURE GENERA OF SPONGILLINAE. | 
In dealing with the sponges of the Lake of Tiberias I have 
found it necessary to examine a large amount of material from 
different parts of the world. As the collection of freshwater 
sponges in the Indian Museum is probably the largest an 
most nearly complete in existence, all known genera being 
represented, I take this opportunity to discuss certain genera 
f obscure status. The genera are Corvospongilla, Annandale ; 
Uruguaya, Carter; Potamolepis, Marshall; and Pachydictyum, 
Weltner. A consideration of their essential features will render 
it possible to indicate more precisely the relationship of 
Cortispongilla and Nudospongilla, and of the Potamolepidinae 
tion is Veluspa, Miclucho-Maclay, from which I find it 
family circle. In a short pa P ve 
pointed out, in agreement ‘with Korotneff * and Svartzevski,’ 
that some of the species assigned to Lubomirskia by Dybowski * 
actually conform to that author’s diagnosis of Veluspa, an 
have further advanced the view that the sponges of Lake Baikal 
probably present a complete transition between the two 
! Ann. Mus. Zool. Ac. Sci. St. Pétersbourg, 1913 (ined.). 
2 Biol. Centralbl., xxi, p. 306 (1901). 
8 Zapiski Kiev. Obshch., xvii (2) (1901). 
4+ Mem. Ac. Sci. St. Petersburg (7) xxvii, No. 6, p. 11 (1880). 
